In a typical cellular system, also referred to as a wireless communications network, wireless devices, also known as mobile stations and/or User Equipment (UE) units communicate via a Radio Access Network (RAN) to one or more Core Networks (CN). The wireless devices can be mobile stations or UE units such as mobile telephones also known as cellular telephones, and laptops with wireless capability, e.g. mobile termination, and thus can be, for example, portable, pocket, hand-held, computer-comprised, or car-mounted mobile devices which communicate voice and/or data with a radio access network.
The radio access network covers a geographical area which is divided into cell areas. Each cell area is served by a base station, e.g. a Radio Base Station (RBS), which in some networks is also called NodeB or B node or Evolved NodeB (eNB, eNodeB) and which in this document also is referred to as a base station. A cell is a geographical area where radio coverage is provided by the radio base station equipment at a base station site. Each cell is identified by an identity (Id, ID) within the local radio area, which is broadcast in the cell. The base stations communicate over the air interface operating on radio frequencies with the UE units within range of the base stations.
In some versions of the radio access network, several base stations are typically connected, e.g. by landlines or microwave, to a Radio Network Controller (RNC). The radio network controller, also sometimes termed a Base Station Controller (BSC), supervises and coordinates various activities of the plural base stations connected thereto. The radio network controllers are typically connected to one or more core networks (CN).
The Universal Mobile Telecommunications System (UMTS) is a Third Generation (3G) mobile communication system, which evolved from the Global System for Mobile Communications (GSM), and is intended to provide improved mobile communication services based on Wideband Code Division Multiple Access (WCDMA) access technology. UMTS Terrestrial Radio Access Network (UTRAN) is essentially a radio access network using WCDMA for UE units. The Third Generation Partnership Project (3GPP) has undertaken to evolve further the UTRAN and GSM based radio access network technologies. Long Term Evolution (LTE) together with Evolved Packet Core (EPC) is the newest addition to the 3GPP family.